feat: support HTTPS URLs in PLAYWRITER_HOST + remote access guide

PLAYWRITER_HOST now accepts full URLs like `https://x-tunnel.traforo.dev`
in addition to plain hostnames. Previously it always constructed
`http://${host}:19988` which broke when using traforo tunnels (HTTPS on
port 443).

Added `parseRelayHost()` utility that detects URL protocols and returns
correct HTTP/WebSocket base URLs. Updated all consumers:
- cli.ts: getServerUrl()
- mcp.ts: getLogServerUrl(), checkRemoteServer()
- executor.ts: checkExtensionStatus()
- utils.ts: getCdpUrl() (ws:// → wss:// for HTTPS hosts)

Plain hostnames still work as before (appends :19988).

Added docs/remote-access.md covering:
- Architecture: playwriter serve + traforo tunnel through Cloudflare
- Host and remote machine setup with env vars
- Use cases: remote Mac mini, user support, multi-machine, VM/devcontainer
- Security model: non-guessable URLs, token auth, localhost-only extension
  endpoint, no open ports, visible automation, instant revocation

README.md

@@ -180,28 +180,24 @@ Color-coded: yellow=links, orange=buttons, coral=inputs, pink=checkboxes, peach=
 +---------------------+     (no extension click)      +-----------------+
 ```
 
-## Remote CLI
+## Remote Access
 
-Run CLI from a different machine (devcontainer, VM, SSH) while Chrome runs on your host.
+Control Chrome on a remote machine over the internet using [traforo](https://traforo.dev) tunnels:
 
 **On host:**
 ```bash
-playwriter serve --token <secret>
+npx -y traforo -p 19988 -t my-machine -- npx -y playwriter serve --token <secret>
 ```
 
 **From remote:**
 ```bash
-playwriter --host 192.168.1.10 --token <secret> session new
-playwriter --host 192.168.1.10 --token <secret> -s 1 -e "await page.goto('https://example.com')"
-```
-
-Or with env vars:
-```bash
-export PLAYWRITER_HOST=192.168.1.10
+export PLAYWRITER_HOST=https://my-machine-tunnel.traforo.dev
 export PLAYWRITER_TOKEN=<secret>
 playwriter -s 1 -e "await page.goto('https://example.com')"
 ```
 
+Also works on a LAN without traforo (`PLAYWRITER_HOST=192.168.1.10`). Full guide with use cases (remote Mac mini, user support, multi-machine control): [docs/remote-access.md](./docs/remote-access.md)
+
 ## Security
 
 - **Local only**: WebSocket server on `localhost:19988`